Residents in Derry have been warned about a door-to-door scam by people pretending to be from the "health board".

In a statement, the Western Health and Social Care Trust said it had become aware of individuals calling to people's doors, claiming to represent organisation and asking residents to fund heart procedures at Altnagelvin Hospital.

"The Western Trust would like to advise members of the community to be vigilant, to inform elderly or vulnerable dependants about these incidents, and contact the police of any suspicious activity," it said in a statement.

A Facebook post warning local residents has been shared more than 200 times, with a number of people commenting below the post that someone had called to their door.

While members of the public have been warned to be more vigilant, local independent councillor Gary Donnelly believes that the reports of bogus callers may be down to a misunderstanding about individuals from a charity doing door-to-door collecting.

Mr Donnelly said that he saw at least three teams of two collecting money around the Creggan area, and that "they were wearing identification tags and were being open about it".

"Straight away I said there is no way is that a scam."

It is believed that the individuals were from the Heart Research Institute, an international organisation that fund raise in the UK, New Zealand, Canada, the USA and the Netherlands.

Mr Donnelly said that he had published a Facebook post to inform the public about fundraising work being carried out in the city.

The PSNI advise the public that most callers to their house are genuine, but there may be incidents where they have to deal with bogus callers.

In these circumstances it is recommended that doors are never left unlocked, that the public should use a door chain when answering the door, and should ask for identification from anyone calling to their door.